Solenoid



Oct. 30, 1934. G D BOWER E A 1,978,737

SOLENOID Filed March 23, 1931 2 SheetsSheet l //v vz/v TOE s GEGEGE 0. 156M752 ILL/S QGILLE MW ATTORNEYS Oct. 30, 1934. G. D. BOWER ET AL SOLENOID Filed March 23, 1931 2 Sheets-Sheet 2 INVE/V 702$ 6150;?65 a. sewage 77 w 1H8 H. emu:

swig/MM 4 7' Toe/v5 Y5 Patented Oct. 30, 1934 UNITED STATES PATENT OFFICE Y SOLENOID George D. Bower, Columbia Heights, and Willis H. Gille, St. Paul, Minn, assignors to Minneapolis-Honeywell Regulator Company, Minne-' apolis, Mlnn., a corporation of Delaware Application March 23,

19 Claims.

This invention relates to improvements in solenoids and has, among the objects: to provide a very eillcient plural coil solenoid o! the movable core type, that is one in which the core may be moved by a relatively powerful coil, and may then be held only by a relatively less powerful holding coil, or inwhich both coils act to pull, and one to hold; to provide a device of this class in which a maximum pull and a maximum stroke can be obtained with much less power, and a device in which the holding may be accomplished with a power expenditure for example of only six-tenths of a watt, as against approximately eight watts necessary in other types of devices of this class; to provide a plural coil solenoid structure in which two armatures operate at opposite sides of a magnetic element in a manner to increase the flux in that region; to utilize one of the armatures as a switch control element; to cause this switch control armature to move when the plunger engages the magnetic element after entry into the field of one of the coils; to provide retarding elements to prevent flux drop to zero, and to largely prevent flux fluctuation in any portion of the magnetic field; to connect a switch in the coil circuit in a manner to interrupt the circuit to one coil; and generally to provide a device of the class described which is unusually efiicient for all purposes for which such devices may be used.

Features of the invention include all the details of construction along with the broader features of the invention which are claimed, in combination and in sub-combination.

Objects, advantages and features oi the in-: vention will be pointed .out in the description of the drawings forming a part of this application, and in said drawings Figure l is a vertical section through the inn proved solenoid structure showing its application to the operation of a valve;

Figure 2 is a bottom view of the valve casing;

Figure 3 is an elevation partly in section illus= trating the connection of the device, with an elec-- trical control circuit;

Figure 4 is a vertical section taken on line -4- of Figure 3 further illustrating the arrangement of the electrical connections; and.

Figure 5 a plan section on line 5-5 of Fig= ure 1. 1

This movable core solenoid construction is herein shown for operating a valve, but although the valve construction, as a whole, is claimed, the various sub-combinations, of solenoid elements, per se, are also claimed,

1931, Serial Nb. 524,826

Numeral 1 indicates the valv'ecasingfthe up: per part of which has a horizontal flange 2 having a circumferential shoulder 3, and a circumferential depression 4 in which rests a gasket 5. Arranged within the tubular section 1 and of substantially less diameter than the inside diameter of said section, is a tube 6 having at its top a flange 7 which engages the upper surface of the packing 5. The parts 6 and 7 are of steel, or other magnetic material. In contact with the top of the flange or plate '7 is a washer 8 also 0!.- steel. It is conceivable that a washer equal in thickness to the combined thickness of elements 7 and 8 may be substituted therefor and the extension 6 suitably connected to the washer.

On top of the steel washer 8 is arranged an insulating washer 9. The washer 8 and flange 1 are detachably connected to the flange 2 by means of suitable screws 10 which compress the flange 7 against the packing 5 to form a sealed connection. Passing upwardly through the element 6 to the top of the solenoid, is a plunger tube 15 of suitable material, the lower end 16 of which is suitably sealingly soldered to the tube 6. The upper portion of this tube is interiorly threaded as at 17. On the outside of the plunger tube 15 and embracing it are contactingly arranged in superposed succession, a steel sleeve 18 (the lower end of which contacts the upper surface of washer 8), a copper sleeve 19, a steel 0 sleeve 20, a steel washer 21, a steel sleeve 22, a copper sleeve 23, a brass washer 24, and a steel ring 26. The steel washer 21 is faced on opposite sides with washers of insulating material indicated at 30 and the lower surface of the brass washer 2 is similarly faced as at 31. The lower coil is indicated at 35 and the upper coil at 36. These coils are disposed between washers 8 and 21. and 21 and 24.

A stop of steel indicated at ll, closes the upper part of the tube and is in threaded connec= tion with threads 17. This stop has a head or flange 41 which contacts the brass washer This flange is circular and is spaced from the inner surface of the steel ring 26 to form an L The step acts to secure annular air gap 42. the various washers and sleeves in operative position, and also sealingly close the tube, 'Iviounted upon the steel ring 26 is a post 345 having thereon an insulating sleeve Mounted on the upper reduced end of the insulating sleeve 46 is a terminal eye 47 of" conductor Telescopically cooperating with the upper reduced portion of the insulating sleeve to is another insulating sleeve 50 which is clampingly iu'ged against the upper surface of the element 47 by a nut 51 in threaded engagement with the post 45, acting through a spring washer 52. The element 4'7 is thus insulated from the post 45.

Mounted :at the top of the ring 26 is a spring switch arm 60 which has "an opening 61 therein loosely traversed by the insulating sleeve 46. The opposite end of this spring arm rests upon a metal grounding washer 62 supported by steel washer 26, and a clamping terminal binding and grounding screw 63 secures terminal of conductor 64 in electrical contact with the arm 60, To the lower side of this arm is secured, by suitable means 6'7,

a steel armature 66, in the form of a circular plate. Normally, as shown in Figure 1, the armature is spaced from the cap 40 and the steel ring 26, the upper surfaces of these elements being coplaner. On energization of the coils as hereinafter more fully described, the armature is drawn down into engagement with elements 40-26 at which time contact between spring 60 and the terminal plate 4'7 is broken and, therefore, in this case the circuit to the pulling coil is broken. A cover 69 encloses the coils and switching structures and rests on shoulder 3.

The plunger is indicated at '70 and has a lower reduced portion '71 to which is suitably attached a valve 72, which cooperates with a suitable valve seat 73 of casing 1. A by-pass valve is indicated at '75 controlling openings '76'7'7, so that when valve '72 is closed, a certain flow may be had through the passage formed by the elements '76 Referring to Figure 3, the conductor 48 which is connected with the clip or eye 4'7, is connected to the lower terminal of the lower coil. The spring arm 60 is grounded on the steel ring, as at 62-63, and a lead 64 connects the terminal of the element 60 with the lower terminal of the upper coil. The upper terminal of the upper coil is connected by conductor 78 with binding post R, mounted on insulated plate 80, the plate being held by suitable screws 81 to the valve casing 1. The valve casing provides a chamber 82 (see Figure 4) which is closed by the cover 80. The upper terminal of the lower coil is connected by conductor 65, with binding post B. The ground conductor 25 connects binding post W with the lower washer '7 as at 68. One means for automatically controlling solenoid operation is described under the heading "Operation.

A valuable feature of the invention relates to the conical or tapered formation of the upper part of the plunger '70. This tapered portion is indicated at 80. In the end of the plunger is a plug 81 which extends slightly therebeyond, to engage stop 40. The relation of the line 79 (representing the base of the tapered portion) to the upper coil, or to the magnetic field of the upper coil, is an important feature. The dotted position of this line, when the plunger is in its limit position, is indicated in the drawings.

In practice, the plunger is made of cold rolled steel or its magnetic equivalent. The upper end is flat except for the anti-stick plug 81 of nonmagnetic material which projects a few thousandths of an inch. The tapering has a marked effect on the shape of the pull curve of the graph of a solenoid constructed in accordance with the teachings of this invention. The relative proportions of the steel stop and the copper and steel sleeves also modify this pull curve. The functions resultant from the various constructions above described will now be more fully explained.

The sleeves function not only as spacers, but

the steel sleeves act to increase the area of the air gap between the steel washer and plunger, thereby shortening the effective air gap and reducing magnetic reluctance at these points. The copper sleeves act asretarding coils controlling changes in the amount of magnetic flux in the 'magnetic circuits to the extent that while current is flowing in the coils, there is always a magnetic flux in the magnetic circuit, so that humming is prevented. The proportions of these sleeves, therefore, also affect the operation of this magnetic circuit.

It is also one of the objects of the present invention to obtain even graduated pull over comparatively long distance of plunger travel. The copper rings act as retarding coils, and may be said to act to prevent a flux drop to zero. The retarding ring 19 tends to prevent any fluctuation in any portion of the magnetic field which may be active in that region, whenthe plunger is in its uppermost dotted line position.

An ordinary solenoid has a maximum pull near the center of its stroke, and a zero pull at the top. Another type of solenoid has a maxi.- mum pull over a greater period of motion, but the pull falls to zero at'the end of the stroke. In the present type of solenoid, the pull increases inversely in proportion to the reduction in air gap between the top of the plunger and the stop, giving a proportionately very great pull while the plunger is resting against the stop. This makes it possible, in this instance, to hold the valve open with a very small amount of power, and the combination gives a longer stroke with heavier initial pull and no weakening at any point in the stroke. This is not possible by any other type of magnetic circuit known to us.

The invention herein is also concerned with the construction of a double coil solenoid for use with direct current. It will be noted that one of the windings is quite heavy for lifting purposes to open the valve, and that the other is much lighter and only functions to hold the plunger after lifting.

Operation When a suitable circuit is made, such as by the special form of thermostat, shown in the diagram, current is supplied to the upper coil 36, but the amount supplied is too small to raise the plunger. When the thermostat is fully closed, current flows to the lower coil in sufiicient quantity to lift the plunger. At this time, both coils are energized. Numeral 100 indicates a stepdown transformer, the high side of which is indicated at 101 and the low side at 102.

The thermostat has two contacts W, B, sequentially engageable by the circuit closer R. On making at R, W the circuit through the holding coil is as followsr one side of 102, 104, W, R, 105 to post R, '78, 64, ground 62, ground 68, 25, W, 106 to 102. On continued motion of R in the same direction, R closes the circuit across W, B to energize the lower coil. The circuit is as follows: 102, 104, W, R, B, 107, B, 65, pulling coil 35, 48, 60, ground 62, ground 68, 25, W, 106, 102.

The control armature 66 at the top of the device, remains in its upper or closed circuit position until the plunger is within a very short distance of the stop 40, at which time the armacoil and de-energizes this coil. A very small in the valve casing 1.

current in the top coil is now sumcient to hold the armature 66 down against the action or the spring arm 60, and to also hold the plunger in its up position. It will be 'noted that both plunger and armature are in contact with the stop cap 40. The reason .why the armature 86 does not pull down before the plunger substantially reaches the top of its stroke, is that, in addition to the air gap between the armature 66, and the stop 40 and the washer 26, there is an air gap between the bottom of the stop, and the washer 21. This latter gap introduces sufilcient reluctance into the magnetic circuit of the other coil to reduce the flux passing between the upper washer, armature and stop, to accomplish the result mentioned. As soon as the plunger makes contact with the stop, the decrease in reluctance (due to introduction of iron into the magnetic field) in the upper circuit is sufficient to cause a great increase of effective fiux at the armature so that it is pulled downwardly.

A notable feature is that even with full current flowing in both coils the plunger must be substantially at the top of its stroke before the armature will pull down, and even with the full current in both coils and with the armature down, the pulling of the plunger away from the, stop by hand will decrease the flux at the armature sufficient to allow the armature to move upwardly to circuit-closed position. The armature, therefore, tends to prevent chattering of the plunger at low voltage since if there lsenoughcurrent to raise the plunger at all, it will stay after reaching its upper position.

In thlscase the plunger operates in the tube 15, which is in communication with the fiuid The opposite end of the tube is closed by the plug 40, and the armature 66 is arranged outside of the tube in opposition to the plug. The switch armature is controlled by the plunger in this sealed tube. Insofar as we are aware, no plunger ever before controlled anything (like a switch) at the outside of the sealed tube. In this case the switch contact is at the outside of a fluid filled plunger chamber.

In the present embodiment, the switch is closed when the armature 66 is in open position but insofar as the magnetic switch is concerned, the closing movement of the armature 66 might as well close a switch.

The approximate ratio between the power input to the lifting coil, and the holding or upper coil is about thirteen to one.

The taper'on the plunger, as before stated, is used to make the magnetic pull on the holding coil eiTective at a point farther along the path of the plunger. If the plunger were not tapered, it would not rise to the desired extent and engage the plug, without the use of a considerably more powerful coil. By tapering, maximum power for holding is obtained at the time when the plunger is firmly seated against the plug. With a straight plunger, there is a sudden increase in power just as the plunger passes through the center washer, there being a drop in power above this point, and before a final increase near the stop. Tapering the plunger at the top widens the air gap between the plunger and the center washer until the tip of the plunger is within the denser field of flux next to the stop. It is desirable for the plunger to seat against the plug or stop because, by this means, the strength of the magnetic field is increased to such an extent that the armature 66 is pulled down and its engagement with the plug and the annulus addi- '3 tiolnally increases the strength of the holding fie d.

We claim as our'invention:

1. A solenoid system, comprising a pair of coils linearly arranged, and a plunger operative in said coils and of a length at least substantially equal to combined coil length, said plunger being substantially normally within only one of the coils, a stop for limiting plunger motion after entry into the field or the other coil, said plunger being tapered at that end nearest the stop and the length oi the tapered portion being such that when the plunger is engaged against the stop. the tapered portion extends into the field of the other coil.

2. A solenoid system comprising a pair of coils linearly arranged, and a plunger operative in said coils and of a length-at least substantially equal to combined coil length, said plunger being substantially normally within only one of the coils. a stop for limiting plunger motion after entry into the field oi the other coil, said plunger being tapered at that end nearest the stop and the length of the tapered portion being such that when the plunger is engaged against the stop the tapered portion extends into the field of the other coil, and means associated with the stop and that coil into the field of which the plunger enters for increasing the magnetic fiux in said coil after engagement of the plunger with the stop.

3. A solenoid system comprising a first coil and a second coil, and a plunger operative by the coils and normally only in the field of one, and adapted to be projected into the field of the other, a stop in the first coil for limiting plunger motion, and having a portion exposed outside of the coil, a metal annulus surrounding and spaced,

from the exposed portion, an armature yieldably held in spaced opposition to ring and stop, said plunger being tapered at that end nearest the stop, the length of the tapered portion being such that when the plunger is engaged against the stop the tapered portion extends into the field of the second coil.

4. A device of the class described including two coils, a plunger movable in the coils and normally within one coil and adapted to enter the other as result of coil energization, a stop of magnetic material arranged to have one side engaged by the end of the plunger after entry into the magnetic field of the last mentioned coil, an armature engageable with the other side of the stop, and means normally holding the armature out of contact with said stop, that end of the plunger nearest said stop being tapered convergently in direction of the stop.

5. A device of the class described including two coils, a plunger movable in the coils, a washer of non-magnetic material adjacent the end of one of the coils, a stop of magnetic material contacting the washer, and arranged to have one end engaged by the end of the plunger after entry into the magnetic field of that coil, a ring of magnetic material surrounding the stop and contacting said washer and forming with the stop an annular air gap, an armature engageible with the ring and stop, and means normally holding the armature out of contact with said ring and stop.

6. A device of the class described including a first coil having a relatively large number of ampere turns, a second coil having a relatively small number of ampere turns, a plunger movable in the coils, a series of elements disposed between the coils and plunger to increase the area of the gap therebetween including a terminal washer of non-magnetic material adjacent theplunger having that end nearest the stop terminally tapered convergently in direction of the pl g.

7. A device of the class described having a plurality of coils, a plunger adapted to move in said coils, a stop against one side of which said plunger engages as a result of coil energization, an armature adapted to contact the opposite side of the stop, means yieldably holding the armature spaced from the stop, and an annulus associated with said stop to form therewith an annular air gap, and also engageable by said armature.

8. A device of the class describedcomprising first and second coils, a plunger adapted to move in said coils, a stop for the first coil against one side of which said plunger engages, an armature adapted to contact the opposite side of the stop, means yieldably holding the armature spaced from the stop, an annulus associated with said stop to form therewith an annular air gap, and also engageable by said armature, a switch operable by said armature, and circuit connections for the coils having said switch therein, and so arranged that after coil energization, the armature moves against the stop to open the switch and interrupt the circuit only to the second coil.

9. A device of the class described comprising first and second coils, atube surrounded by said coils, a plunger in said tube having'a' tapered end adapted to move into the field of the first coil,

said tube having a stop against one side of which said plunger engages after entry into the field, an armature arranged outside the tube and adapted to contact the opposite side of the stop, an annulus associated with said stop to form an annular gap, and engageable by saidarmature, a switch operable by, said armature and circuit connections for the coils having said switch therein, and so arranged that after coil energiza- 7/ tion, the armature moves against the stop to open the switch and interrupt the circuit only to the second coil.

10. A device of the class described including a tube, a plunger slidable in the tube, elements surrounding the tube in linear sequence including a first steel washer, a first steel sleeve engaging the washer, a copper sleeve engaging the steel sleeve, and a second steel sleeve engaging the copper sleeve, a second steel washer engaging the second steel sleeve, a coil having a relatively large number of ampere turns and surrounding said sleeves and disposed between said washers, additional elements surrounding the tube in linear sequence including a steel sleeve engaging the second washer, a copper sleeve engaging the steel sleeve, a washer of non-magnetic material engaging the copper sleeve, a steel plug closing the tube and extending thereinto, and engaging said non-magnetic washer, a steel ring engaging the non-magnetic washer and forming with the plug an annular gap, a coil having arelatively small number of ampere turns surrounding the sleeves and disposed between the steel and non-magnetic washers, an armature engageable with the ring and plug, and means yieldably holding the armature out of contact with ring andv plug, said plunger having the end nearest the plug terminally tapered, convergently in direction of the plug.

11. A device of the class described including a tube, a plunger slidable in the tube, magnetic and non-magnetic elements surrounding the tube in linear sequence, washers arranged terminally of said elements, a coil having a relatively large number of ampere turns and surrounding said sleeves and disposed between said washers, additional magnetic and non-magnetic elements surrounding the tube in linear sequence, terminating in a non-magnetic washer, a steel plug closing the tube and engaging said terminal non-magnetic washer, a steel ring engaging the brass washer and forming with the plug an annular gap, a coil having a relatively small number of ampere turns surrounding the last mentioned sleeves, an armature engageable with the ring and plug, means yieldably holding the armature out of contact with ring and plug, a switch adapted to be moved by the armature, and circuit connections for the coils including said switch and adapted to permit energization of the coils while the switch is closed, adapted to de-energize the first coil after engagement of the plunger with the stop and of the armature with the plug and ring, and adapted to maintain energization of the second coil after such engagement, said plunger having the end nearest the plug terminally tapered, convergently in direction of the plug.

12. A device of the class described including a tube, a plunger slidable in the tube, elements surrounding the tubein linear sequence including a first steel washer, a first steel sleeve engaging the washer, a copper sleeve engaging the steel sleeve, and a second steel sleeve engaging the copper sleeve, a second-steel washer engaging the second steel sleeve, a coil having a relatively large number of ampere turns and surrounding said sleeves and disposed between said washers, additional elements surrounding the tube in linear sequence including a steel sleeve engaging the second washer, a copper sleeve engaging the steel sleeve, a brass washer engaging the copper sleeve,

a steel plug closing the tube and extending thereinto and engaging said brass washer, a steel ring engaging the brass washer and forming with the plug an annular gap, a coil having a relatively small number of ampere turns surrounding the sleeves and disposed between the steel and brass washers, an armature engageable with the ring and plug, means yieldably holding the armature out of contact with ring and plug, a switch adapted to be moved by the armature, and circuit connections for the coils, including said switch and adapted to permit energization of the coils while the switch is closed, adapted to de-energize the first coil after engagement of the plunger with the stop and of the armature with the plug and ring, and adapted to maintain energization of the second coil after such engagement, said plunger having that end nearest the plug terminally tapered, convergently in direction of the plug.

13. A pair of solenoid coils, a plunger operable by said coils, circuits by which energization of the coils is obtainable, and a switch controlling the circuit to one of the coils, and arranged and adapted to be magnetically opened as a result 01. increased magnetic field in one of the coils, and

means by which the circuits are initially sequentially operated, the switch circuit first.

14. A pair of solenoid coils, a plunger operable by said coils, a switch adapted to control said coils including circuits by which sequential energization of the coils is obtainable, and a switch in the circuit of one of the coils arranged and adapted to be opened as the result of increased magnetic field in that coil due to introduction of said plunger into said field as the result of energization of the other coil.

15. A pair of solenoid coils, a plunger operable by said coils, a switch adapted to control said coils including circuits by which sequential energization of the coils is obtainable, and a switch in the circuit of that coil which is last energized arranged and adapted to be opened as the result of increased magnetic field in the coil first energized due to introduction of said plunger into said field as the result of energization of the coil which is last energized.

16. A device of the class described including a switch automatically movable, two contacts sequentially engageable by said switchelement as it moves in one direction, a magnetically operable device including a first coil and a second coil and a plunger adapted to be translated in one direction by the second coil and to enter the magnetic field of the said first coil, a circuit for the first coil which is closed when the automatically movable switch element engages one of the contacts, a circuit for the second coil which is closedwhen said automatically movable element engages its other contact, said circuit for the second coil including a switch arranged and adapted to be opened by the first coil as result of an increase of strength of its magnetic field due to introduction of the plunger into said field.

17. In combination, a member to be controlled having a first and a second position and being biased toward the first position, power means to move said member to its second position, maintaining means to hold said member in its second position after movement thereto by the power means, control circuits associated with said power means and maintaining means; control means for said control circuits, and arranged upon movement in one direction to cause energization of the maintaining means and on further movement in the same direction to cause energization of the power means; and switching mechanism associated with said member for de-energizing the power means when said member has been moved to its second position, said maintaining means maintaining said member in its second position until de-energized as a result of movement of said control means in the opposite direction beyond the point at which energization of said power means and maintaining means took place.

18. In combination, a member to be controlled having a first and a second position and being biased toward the first position, motor means to move said member to its second position, electromagnetic means to hold said member in its second position after movement thereto by the motor means; a thermostat and control circuits associated with said motor means and electro-magnetic means, said thermostat arranged upon movement in one direction to cause energization of the electro-magnetic means and on further movement in the. same direction to cause energization of the, motor means; and switching mechanism associated with said member for de-energizing the motor means when said member has been moved to its second position, said electromagnetic means maintaining said member in its second position until de-energized as a result of movement of said thermostat in the opposite direction beyond the point at which energization of said power means and electro-magnetic means took place.

19. A pair of solenoid coils, a plunger operable by the coils, a switch, and a controlarmature for the switch associated with the coils, stop means at the opposite sides of which said plunger and armature operate said switch controlling the circuit to one of the coils, and adapted to be opened as the result of increased magnetic field in that coil, and means by which the circuits are initially sequentially operated, the switch circuit first.

GEORGE D. BOWER. ms H. GILLE. 

